1. Field of the Invention
This invention relates generally to pneumatic safety devices for Diesel engines, and more particularly to a safety air supply for use in combination with pneumatic shutdown systems of the type connected to an existing air supply source and cooperative through electromechanical control means with the fuel injectors of Diesel engines for moving the fuel injectors between operative and inoperative positions.
2. Brief Description of the Prior Art
Safety devices for Diesel and other internal combustion engines are known in the art. Many trucks having diesel engines have a pneumatic "Shutdown" cylinder which moves the fuel injectors from an operative position to a neutral position. On some models, the shutdown cylinder is connected to the existing air compressor or air reservoir by plastic tubing. If the truck is involved in a wreck, turns over or catches on fire, the plastic tubing may be destroyed. In such cases, control of the shutdown cylinder is lost and the driver is unable to turn off the engine because the fuel injectors continue pumping.
One exemplary "shutdown system" for trucks is a device manufactured by Kysor of Cadillac, a division of Kysor Industrial Corporation, 1100 Wright St., Cadillac, Mich. 49601. The Kysor device comprises an operator controlled air valve connected to the existing air compressor which is bolted to the engine block and activates a lever connected to a rack to move the fuel injectors into and out of the firing position. When the injectors are retracted, fuel circulates back to the reservoir. The device is connected to the existing air compressor by plastic tubing which will easily melt in a fire or may become damaged by everyday usage. The air valve is actuated by the driver from inside the vehicle by pulling a lever which often is inoperative or stiff due to lack of use. The lever would also be difficult and dangerous to reach in the event of a fire or accident. When the plastic tubing is damaged, the injectors can not be moved out of the firing position and fuel continues circulating into the firing chambers. Should the injectors be locked out of the firing position, the engine can not be restarted.
There are several patents which disclose various safety devices for Diesel and other internal combustion engines. Most are directed toward valves installed between the fuel pump and the combustion chamber, or on the fuel pump to render the fuel pump inactive or to displace the fuel with air to stop the engine.
Santschi, U.S. Pat. No. 2,095,349 discloses a safety device for engines which operates in a manner similar to a governor. A rotary element of a safety stop mechanism contains a tripping arm and has a finger which extends outward upon sufficient centrifugal force to open a valve allowing air to flow from a source to displace fuel from the fuel pump. The device stops the engine by terminating the fuel feed responsive to engine speed in excess of the normal speed of the engine.
Rachuig, U.S. Pat. No. 2,714,290 discloses a control device for shutting down one or more internal combustion engines simultaneously in an emergency. The device is particularly designed for pipe line operations where engines were arranged in a pump house. An air intake line has a first pressure responsive valve arranged therein and a feed line connected to a source of fuel and to the engine has a second pressure responsive valve located therein. The two valves are connected to a source of pressure to maintain them in an open position. Remote quick release valves located in the pressure supply line release pressure from the first and second valves to close them sequentially in reverse order responsive to the opening of the quick release valve.
Metzger, U.S. Pat. No. 2,714,883 discloses a pneumatic starting and shutdown system for engines upon failure of any one of the various parts of the engine unit beyond the safe limits of operation, such as a drop in oil pressure, an increase in water jacket temperature, an increase in engine speed, a loss in supply air pressure, etc., and primarily to cut off the supply of fuel to the engine, and whereby the engine cylinders will be thoroughly scavenged of residual gases upon restarting the engine.
Grondel et al, U.S. Pat. No. 3,760,784 discloses an emergency stop device for engines. A bottle of gas under pressure and closed by a diaphragm is received in a hollow body connected through a check valve to the fuel delivery pipe of an internal combustion engine at a point between the reservoir and injection pump downstream of a second check valve. The housing contains a mechanism to pierce the diaphragm in case of an accident to send a charge of the gas into the fuel delivery pipe and in the supply chamber of the injection pump to expel fuel therefrom towards the reservoir through a scavenging valve and thus causing the engine to stop.
Clemens et al, U.S. Pat. No. 4,361,121 discloses a control device for shutting of a Diesel engine. The device includes a supply pump and a reversal valve. The reversal valve in the stop position connects the suction chamber with the intake side of the supply pump and connects the compresssion side of the supply pump with the fuel tank. A check valve is provided in the fuel line between the supply pump and the fuel filter which is disposed to open toward the filter. Another check valve comprising an overflow valve determining the suction line pressure is provided in an overflow line leading from the suction chamber to the fuel tank. When the reversal valve is actuated by an electromagnet, a similar key-actuated shutoff to that known in gasoline engines can also be effected in Diesel engines.
The present invention is distinguished over the prior art in general, and these patents in particular by a safety air supply for use in combination with pneumatic shutdown systems of the type connected to an existing air supply source and cooperative through electromechanical control means with the fuel injectors of Diesel engines for moving the fuel injectors between operative and inoperative positions. The safety device comprises an enclosed air reservoir tank connected between the air supply source and the air cylinder of the shutdown system by heavy duty armored conduit. A tee fitting is sealed in the top wall of the tank and a one-way check valve secured in the top of the tee fitting allows air to enter the tank from the existing source up to a predetermined pressure and thereafter closes to contain a supply of air within the tank independent from the existing source. The outlet of the tee fitting is connected to the inlet of the existing pneumatic shutdown system. In the event of a failure of the air source, or a ruptured or burned air line between the source and the pneumatic shutdown air cylinder, air will be supplied from the air tank to the shutdown air cylinder to maintain control whereby the fuel injectors may be moved to the neutral position or inoperative position.